Can you post the link you are downloading firefox from? It is a possibility you are trying to install a non-official (and malicious) version.

hello, if you've downloaded the file from mozilla.org, it will be clean and the message by IE most likely a false positive. please try it again with the full installer package from https://www.mozilla.org/firefox/all/.

http://www.mozilla.org/en-US/products/download.html?product=firefox-stub&os=win&lang=en-US http://www.mozilla.org/en-US/firefox/new/#download-fx I've tried both of these, neither worked.

Same thing happened with that link, it said it contained a virus and was deleted.

if IE flags every download as malicious this by itself might be a sign of an infection of your system: http://social.technet.microsoft.com/Forums/ie/en-US/c888dbaf-cd4a-40a2-a75a-6927c7d2844c/ie89-says-every-file-contained-a-file-and-was-deleted

It doesn't flag every download as malicious, only the Firefox download. I tried all the solutions on the link, but none worked.

Try to get the full version of the latest Firefox release on the FTP server:

• https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/latest/win32/en-US/

Try using Safari, that's what I had to do